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MAN PAGE: FSTAB(5)Contents
fstab - static information about the filesystems
#include <fstab.h>
The file fstab contains descriptive information about the
various file systems. fstab is only read by programs, and
not written; it is the duty of the system administrator to
properly create and maintain this file. Each filesystem
is described on a separate line; fields on each line are
separated by tabs or spaces. The order of records in
fstab is important because fsck(8), mount(8), and
umount(8) sequentially iterate through fstab doing their
thing.
The first field, (fs_spec), describes the block special
device or remote filesystem to be mounted.
For ordinary mounts it will hold (a link to) a block spe
cial device node (as created by mknod(8)) for the device
to be mounted, like `/dev/cdrom' or `/dev/sdb7'. For NFS
mounts one will have <host>:<dir>, e.g., `knuth.aeb.nl:/'.
For procfs, use `proc'.
Instead of giving the device explicitly, one may indicate
the (ext2) filesystem that is to be mounted by its UUID or
volume label (cf. e2label(8)), writing LABEL=<label> or
UUID=<uuid>, e.g., `LABEL=Boot' or `UUID=3e6be9de-8139
-11d1-9106-a43f08d823a6'. This will make the system more
robust: adding or removing a SCSI disk changes the disk
device name but not the filesystem volume label.
The second field, (fs_file), describes the mount point for
the filesystem. For swap partitions, this field should be
specified as `none'. If the name of the mount point con
tains spaces these can be escaped as `\040'.
The third field, (fs_vfstype), describes the type of the
filesystem. The system currently supports these types of
filesystems (and possibly others - consult /proc/filesys
tems):
minix a local filesystem, supporting filenames of length
14 or 30 characters.
ext a local filesystem with longer filenames and larger
inodes. This filesystem has been replaced by the
ext2 file system, and should no longer be used.
ext2 a local filesystem with longer filenames, larger
inodes, and lots of other features.
xiafs a local filesystem with longer filenames, larger
inodes, and lots of other features.
msdos a local filesystem for MS-DOS partitions.
hpfs a local filesystem for HPFS partitions.
iso9660
a local filesystem used for CD-ROM drives.
nfs a filesystem for mounting partitions from remote
systems.
swap a disk partition to be used for swapping.
If fs_vfstype is specified as ``ignore'' the entry is
ignored. This is useful to show disk partitions which are
currently unused.
The fourth field, (fs_mntops), describes the mount options
associated with the filesystem.
It is formatted as a comma separated list of options. It
contains at least the type of mount plus any additional
options appropriate to the filesystem type. For documen
tation on the available options for non-nfs file systems,
see mount(8). For documentation on all nfs-specific
options have a look at nfs(5). Common for all types of
file system are the options ``noauto'' (do not mount when
"mount -a" is given, e.g., at boot time), and ``user''
(allow a user to mount). For more details, see mount(8).
The fifth field, (fs_freq), is used for these filesystems
by the dump(8) command to determine which filesystems need
to be dumped. If the fifth field is not present, a value
of zero is returned and dump will assume that the filesys
tem does not need to be dumped.
The sixth field, (fs_passno), is used by the fsck(8) pro
gram to determine the order in which filesystem checks are
done at reboot time. The root filesystem should be speci
fied with a fs_passno of 1, and other filesystems should
have a fs_passno of 2. Filesystems within a drive will be
checked sequentially, but filesystems on different drives
will be checked at the same time to utilize parallelism
available in the hardware. If the sixth field is not pre
sent or zero, a value of zero is returned and fsck will
assume that the filesystem does not need to be checked.
The proper way to read records from fstab is to use the
routines getmntent(3).
/etc/fstab The file fstab resides in /etc. The documentation in mount(8) is often more up-to-date.
getmntent(3), mount(8), swapon(8), fs(5) nfs(5)
The fstab file format appeared in 4.0BSD.
Linux 2.2 15 June 1999 3 |
